From 97a10d2a6b9cde6ffb58471438c5334f795da89d Mon Sep 17 00:00:00 2001
From: morrySnow <101034200+morrySnow@users.noreply.github.com>
Date: Mon, 13 May 2024 14:42:04 +0800
Subject: [PATCH] [fix](Nereids) cast from json should always nullable (#34707)

---
 .../doris/nereids/trees/expressions/Cast.java  |  2 ++
 .../suites/query_p0/cast/test_cast.groovy      | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/Cast.java b/fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/Cast.java
index 76cb1826e55113..62bd3639b5a244 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/Cast.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/Cast.java
@@ -79,6 +79,8 @@ public boolean nullable() {
             return true;
         } else if (!childDataType.isTimeLikeType() && targetType.isTimeLikeType()) {
             return true;
+        } else if (childDataType.isJsonType()) {
+            return true;
         } else {
             return child().nullable();
         }
diff --git a/regression-test/suites/query_p0/cast/test_cast.groovy b/regression-test/suites/query_p0/cast/test_cast.groovy
index c0df52b39e7ddf..2fe4d53eb80a09 100644
--- a/regression-test/suites/query_p0/cast/test_cast.groovy
+++ b/regression-test/suites/query_p0/cast/test_cast.groovy
@@ -145,4 +145,22 @@ suite('test_cast', "arrow_flight_sql") {
         sql "select * from ${tbl} where case when k0 = 101 then 'true' else 1 end"
         result([[101]])
     }
+
+    sql "DROP TABLE IF EXISTS test_json"
+    sql """
+        CREATE TABLE IF NOT EXISTS test_json (
+          id INT not null,
+          j JSON not null
+        )
+        DUPLICATE KEY(id)
+        DISTRIBUTED BY HASH(id) BUCKETS 10
+        PROPERTIES("replication_num" = "1");
+    """
+
+    sql """
+        INSERT INTO test_json VALUES(26, '{"k1":"v1", "k2": 200}');
+    """
+    sql "sync"
+    sql "Select cast(j as int) from test_json"
+    sql "DROP TABLE IF EXISTS test_json"
 }